1. Technical Field
The present invention relates to a turn signal indicator device for a vehicle.
2. Background Art
For example, in the case where a vehicle changes its course by turning right or left at a road intersection (hereinafter, which vehicle's operation to change its course by turning right or left will be designated as course change), a driver should indicate a turn signal (display) so that drivers of the other vehicles can recognize the turn signal. Also in the case where, for example, a vehicle changes its traveling lane in a road having a plurality of lanes running in parallel (hereinafter, which vehicle's operation to change a traveling lane will be designated as lane change), a driver should indicate a turn signal.
Besides, the turn signal for the lane change may be performed merely for about several seconds in changing the lane. On the other hand, the turn signal for the course change needs to be continuously performed before starting the course change until completion of the course change.
In order to indicate a turn signal in such cases, a vehicle is provided, as a turn signal indicator, turn signal lamps in right and left portions on its body. Besides, in order to cause the right or left turn signal lamp to flash in the course change or the lane change, a turn signal indicating operation lever operable by a driver is provided in a portion of a steering column disposed in front of a driver's seat.
The turn signal indicating operation lever can be vertically swung as illustrated in FIG. 8 by a manual operation of a driver in general. This operation lever is usually in a neutral position P0, can be moved to an operation position PL1 or PL2 by raising the right end of the lever and can be moved to an operation position PR1 or PR2 by pushing down the right end of the lever.
Besides, when the operation lever is moved to the operation position PL1 or PR1, this lever operates as a momentary switch. When the driver releases a force applied to this operation lever, the operation lever automatically returns to the neutral position P0 from the operation position PL1 or PR1 by a force of a spring or the like.
On the other hand, when the operation lever is moved to the operation position PL2 or PR2, this lever operates as an alternative switch. When this operation lever is moved to the operation position PL2, this operation lever is retained in the operation position PL2 and does not return to the neutral position P0 even if the driver releases a force applied to the operation lever. Similarly, when the operation lever is moved to the operation position PR2, this operation lever is retained in the operation position PR2 and does not return to the neutral position P0 even if the driver releases a force applied to the operation lever. When the operation lever is moved to the operation position PL2 or PR2, the retention of the lever is automatically released if a steering angle of the steering wheel becomes small because of the completion of the course change, and thus, it returns to the neutral position P0.
Accordingly, the driver can continuously indicate the turn signal until the course change is completed by moving the operation lever to the operation position PL2 or PR2 without continuously pressing the operation lever for a long period of time. Alternatively, for the lane change, the driver can indicate the turn signal merely while he/she is operating the operation lever by moving the operation lever to the operation position PL1 or PR1.
Furthermore, a switch for such an operation lever is usually provided with five electric contacts SL1, SL2, S0, SR1 and SR2 as illustrated in FIG. 8. When the operation lever is in the operation position PL1, PL2, P0, PR1 or PR2, one of the electric contacts SL1, SL2, S0, SR1 and SR2 is selectively closed with the other contacts opened. It is noted that the contact corresponding to the neutral position is not provided in some cases.
As related-art techniques related to the operation lever and the turn signal indication described above, those disclosed in JP-A-S61-54333, JP-A-S61-54334, and JP-A-H11-250772 are known.
JP-A-S61-54333 discloses a momentary turn signal switch operable in operation positions of two stages (corresponding to the positions PL1, PL2, P0, PR1 and PR2 of FIG. 8). Besides, an electric circuit for driving a turn signal lamp holds (latches) the turn signal lamp in a driven state in accordance with a signal supplied when the switch is operated to the operation position of the second stage (corresponding to the position PL2 or PR2). Accordingly, although an operation lever of the switch is not mechanically retained also in the position of the second stage, the operation of the turn signal lamp is electrically controlled to be retained in a flashing state.
JP-A-S61-54334 further discloses that even if a switch corresponding to a position of the second stage (corresponding to the contact SL2 or SR2 of FIG. 8) is broken and always in an off state, an operation allocated to the switch corresponding to the position of the second stage can be performed by performing a specific operation, specifically, by turning on a switch corresponding to a position of the first stage (corresponding to the contact SL1 or SR1 of FIG. 8) by a plurality of times in a prescribed period of time.
JP-A-H11-250772 discloses the structure of a specific mechanical part including a turn signal indicating operation lever.